Working hypothesis: Some periodontal pathogens such as Actinobacillus actinomycetemcomitans (Aa), chronic inflammatory agents, are associated with atherosclerotic plaque and constitute an infectious component in cardiovascular disease (CVD). However, to date, no periodontal pathogen, including A.a., has ever been isolated from atheromas, likely due to their fastidious growth and sensitivity to oxygen. To that end we developed a novel approach for the isolation of viable bacteria from existing collection of atheromatous plaques. The method exploits the natural tropism of the bacteria toward human endothelial tissue. As a result, viable A. actinomycetemcomitans were identified. These data suggest that at least in some individuals, Aa invasion of cardiovascular tissues may contribute to the cardiovascular pathology either directly via its own cytotoxic properties or indirectly by inducing inflammation at infected sites. The specific aims of this proposal are 1) to isolate clinical strains from existing carotid atheromatous tissue specimens and 2) to characterize the isolated Aa strains, their invasion phenotype and the cell death process they trigger in host cells. Genetic, biochemical, tissue culture and microscopy methods will be used in this collaborative project. The isolation of viable bacteria upon completion of this study will lead to the identification, characterization and genetic analysis of periodontal clinical strains associated with atherosclerosis. This will contribute to the long-term goal: dissecting the molecular and cellular basis of the interaction of these chronic infectious agents with cardiovascular tissues, thereby determining their role in cardiovascular disease and perhaps ultimately identifying drug targets for prevention and therapy of CVD.